CN115668645A - Waveguide tube slit antenna - Google Patents
Waveguide tube slit antenna Download PDFInfo
- Publication number
- CN115668645A CN115668645A CN202180037510.4A CN202180037510A CN115668645A CN 115668645 A CN115668645 A CN 115668645A CN 202180037510 A CN202180037510 A CN 202180037510A CN 115668645 A CN115668645 A CN 115668645A
- Authority
- CN
- China
- Prior art keywords
- waveguide
- radiation
- slot antenna
- waveguide slot
- antenna device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
- H01Q13/10—Resonant slot antennas
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/24—Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
- H01Q15/14—Reflecting surfaces; Equivalent structures
- H01Q15/22—Reflecting surfaces; Equivalent structures functioning also as polarisation filter
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/0006—Particular feeding systems
- H01Q21/0037—Particular feeding systems linear waveguide fed arrays
- H01Q21/0043—Slotted waveguides
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Waveguide Aerials (AREA)
- Aerials With Secondary Devices (AREA)
Abstract
A waveguide slot antenna according to an aspect of the present disclosure includes: a waveguide (10) that is provided with a plurality of slits (6) that are provided at predetermined intervals in the central axis direction and that serves as a radiation unit (8) that radiates radio waves; and a concave-convex section (20) provided on the outer wall surface (4) around the radiation section so as to periodically spread from the radiation section. The concave-convex portion is configured to reflect an incident wave of the radio wave from the radiation portion, which is incident from the front in the radiation direction, in a direction different from the incident direction of the incident wave.
Description
Cross Reference to Related Applications
The international application claims priority to japanese patent application No. 2020-90692, filed at the japanese patent office on 25/5/2020, and is hereby incorporated by reference in its entirety.
Technical Field
The present disclosure relates to a waveguide slot antenna including a waveguide in which a plurality of slots are provided at predetermined intervals on a side surface.
Background
As described in patent document 1, a frequency selective surface unit is known which can suppress unnecessary reflection of radio waves from an antenna device. The frequency selective surface unit is configured by providing a cross-shaped annular slit formed by a copper mesh layer having a cross-shaped slit and a cross-shaped copper bar layer arranged in the slit of the copper mesh layer on a dielectric substrate.
According to this frequency selective surface unit, by adjusting the size of the cross-shaped annular slit, it is possible to transmit and receive radio waves from the antenna device and to suppress reflection of the radio waves from the antenna device.
On the other hand, as an antenna device used in a radar device or a communication device, a waveguide slot antenna having a waveguide in which a plurality of slots are provided at predetermined intervals on a side surface is known. In this waveguide slot antenna, since the periphery of the slot is made of metal, if an object such as a radome is provided in front of the radiation direction of the radio wave, the transmission radio wave is reflected by the object, reaches the metal portion around the slot, and is reflected at the metal portion with low loss. Therefore, in the waveguide slot antenna, there is a case where overlapping reflection occurs between an object such as a radome arranged forward in the radiation direction of radio waves and a metal portion of the antenna body.
Patent document 1: CN102723541B.
When the superposition reflection of the radio wave occurs in the waveguide slot antenna, the reflected wave caused by the superposition reflection interferes with the reflected wave from the target object to be detected in the radar device or interferes with the radio wave transmitted from the communication object in the communication device. Therefore, the overlapped reflection in the waveguide slot antenna is an important factor for deterioration of the target object detection performance of the radar device and the communication performance of the communication device.
In contrast, according to the frequency selective surface unit described in patent document 1, reflection of radio waves can be suppressed. Therefore, if the frequency selective surface unit described in patent document 1 is disposed in front of the waveguide slot antenna in the radiation direction, the above-described overlapping reflection can be suppressed, and the performance degradation of the radar apparatus and the communication apparatus using the antenna can be suppressed.
However, as a result of detailed studies, the inventors have found a problem that in the frequency selective surface unit described in patent document 1, the frequency of the radio wave that can be suppressed by the cross-shaped annular slit is limited, and therefore the frequency band of the radio wave that can be transmitted and received is narrowed.
Further, the frequency selective surface unit described in patent document 1 is disposed as a so-called filter in front of the radiation direction of the radio wave of the waveguide slot antenna, and therefore there is a problem that the performance of the radar apparatus and the communication apparatus is deteriorated due to the attenuation of the radio wave transmitted and received.
Disclosure of Invention
In one aspect of the present disclosure, it is desirable to suppress, in a waveguide slot antenna, overlapped reflection occurring between an object disposed in front of a radiation direction of radio waves and an antenna main body without using a filter such as a frequency selective surface unit.
A waveguide slot antenna according to a first aspect of the present disclosure includes a waveguide including a plurality of slots provided at predetermined intervals in a central axis direction. The plurality of slits provided in the waveguide function as radiation sections for radiating radio waves.
Further, a concave-convex portion is provided on the outer wall surface around the radiation portion so as to periodically spread from the radiation portion. The concave-convex portion is configured to reflect an incident wave of the radio wave from the radiation portion, which is incident from the front in the radiation direction, in a direction different from the incident direction of the incident wave.
Therefore, according to the waveguide slot antenna of the present disclosure, when a radio wave radiated from the radiation portion collides with an object arranged in front in the radiation direction and is reflected, and the reflected wave enters the antenna device, the incident wave can be reflected in a direction different from the incident direction.
Therefore, it is possible to suppress the occurrence of the above-described overlap reflection in which the reflected wave from the object arranged forward in the radiation direction is reflected from the outer wall surface around the radiation portion toward the object.
Thus, according to the waveguide slot antenna of the present disclosure, the following can be suppressed: since unnecessary noise components are superimposed on radio waves that should be transmitted and received by the waveguide slot antenna due to the superimposed reflection, the performance of a radar apparatus or a communication apparatus using the waveguide slot antenna is degraded.
Further, according to the waveguide slot antenna of the present disclosure, it is not necessary to dispose a filter such as the above-described frequency selective surface unit in front of the radiation direction of the radio wave in order to suppress the overlapping reflection. Therefore, the following can be suppressed: by disposing a filter such as a frequency selective surface unit, the frequency band of the radio wave transmitted and received by the waveguide slot antenna can be narrowed, and the transmission/reception power of the radio wave can be reduced.
Next, a waveguide slot antenna according to a second aspect of the present disclosure is configured by a waveguide including a plurality of slots provided at predetermined intervals in a central axis direction as a radiation unit that radiates linearly polarized radio waves.
Further, a plurality of linear protrusions are provided at intervals on the outer wall surface around the radiation section so as to be inclined at a predetermined angle with respect to the central axis of the waveguide.
The plurality of ridges are configured to reflect an incident wave, which is incident from the front in the radiation direction, of the radio wave from the radiation section, by rotating the polarization plane of the incident wave by a predetermined angle, through the grooves between the ridges and the ridges.
Therefore, according to the waveguide slot antenna of the present disclosure, the following can be suppressed: when a linearly polarized radio wave radiated from the radiation unit is reflected in a manner of being superimposed between an object disposed in front of the radiation direction and an outer wall surface around the radiation unit and is incident on the radiation unit, the incident wave is received by the radiation unit.
Accordingly, in the waveguide slot antenna according to the present disclosure, it is possible to suppress performance degradation of a radar apparatus or a communication apparatus using the waveguide slot antenna due to the above-described superposition reflection.
In addition, in the waveguide slot antenna of the present disclosure, it is also not necessary to dispose a filter such as a frequency selective surface element in front of the radiation direction of radio waves. Therefore, it is possible to suppress narrowing of the frequency band of the radio wave that can be transmitted and received and reduction of the transmission/reception power of the radio wave.
Drawings
Fig. 1 is a perspective view showing the entire configuration of an antenna device according to a first embodiment.
Fig. 2 is an explanatory diagram illustrating an arrangement state of a plurality of waveguides constituting an antenna device.
Fig. 3 is an explanatory diagram illustrating overlapping reflections generated between the antenna device and an object.
Fig. 4 is an explanatory diagram for explaining the shape of the concave-convex portion and the reflection of the radio wave by the concave-convex portion.
Fig. 5A is an explanatory diagram showing reflection characteristics of radio waves of the antenna device without the concave-convex portion.
Fig. 5B is an explanatory diagram showing reflection characteristics of radio waves of the antenna device of the first embodiment.
Fig. 6 is a perspective view showing the entire configuration of the antenna device according to the first modification.
Fig. 7 is a perspective view showing the entire configuration of an antenna device according to a second modification.
Fig. 8 is a perspective view showing the entire configuration of an antenna device according to a third modification.
Fig. 9 is a perspective view showing the entire configuration of an antenna device according to a fourth modification.
Fig. 10 is a perspective view showing the entire configuration of the antenna device according to the second embodiment.
Fig. 11 is an explanatory view for explaining reflection characteristics of radio waves by the ridges and the grooves in the second embodiment.
Fig. 12A is an explanatory diagram showing reflection characteristics of radio waves of the antenna device without the concave-convex portion.
Fig. 12B is an explanatory diagram showing reflection characteristics of radio waves of the antenna device of the second embodiment.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
[ first embodiment ]
The waveguide slot antenna according to the present embodiment is used, for example, as an antenna device for transmitting and receiving a millimeter wave in a 70 to 80GHz band in a millimeter wave radar device mounted on an automobile or the like. Therefore, in the following description, the waveguide slot antenna according to the embodiment will be referred to as an antenna device 2 only.
The antenna device 2 of the present embodiment shown in fig. 1 includes a plurality of waveguides 10 arranged in the X-axis direction of the outer wall surface 4 along the outer wall surface 4 orthogonal to the Z-axis direction which is the radiation direction of radio waves.
The plurality of waveguides 10 are made of metal, and as shown in fig. 2, the central axis O of each waveguide 10 is arranged in the Y-axis direction orthogonal to the X-axis on the outer wall surface 4 of the antenna device 2 and in parallel with each other.
In addition, a plurality of slits 6 are provided in each of the plurality of waveguides 10 at predetermined intervals in the direction of the central axis O of the waveguide 10. Therefore, since the waveguides 10 are arranged in parallel, the slits 6 are arranged at predetermined intervals in the X-axis direction and the Y-axis direction on the outer wall surface 4 of the antenna device 2.
In this way, the plurality of slits 6 arranged in a distributed manner in the X-axis direction and the Y-axis direction function as radiation sections 8 that radiate radio waves in the Z-axis direction from the outer wall surface 4 of the antenna device 2.
In each waveguide 10, the plurality of slits 6 are elongated in the direction of the central axis O of the waveguide 10, and are arranged in the direction of the central axis O of the waveguide 10 at intervals of one-half (λ/2) of the wavelength λ of the central frequency of the radio wave transmitted and received by the antenna device 2.
In each waveguide 10, the plurality of slits 6 are alternately arranged at positions eccentric from the central axis O of the waveguide 10 with the central axis O interposed therebetween. This is to prevent radio waves radiated from the slits 6 from being cancelled out in opposite phases.
Next, in the antenna apparatus 2, a transmission path, a probe, and the like for a high-frequency signal are provided around the plurality of waveguides 10, so that a transmission signal is input to each waveguide 10 or a reception signal is extracted from each waveguide 10.
Further, the configuration of the waveguide 10 in which the plurality of slits 6 are provided, the method of feeding power to the waveguide 10, and the like are known techniques as described in, for example, japanese patent application laid-open No. 2008-167246 and the like, and therefore, detailed description thereof is omitted here.
The outer wall surface 4 of the antenna device 2 extends in the X-axis direction from the plurality of waveguides 10 in order to arrange a transmission path and a probe for a high-frequency signal in the antenna device 2. The outer wall surface 4 around the waveguide 10 is made of the same metal as the waveguide 10.
As shown in fig. 1, in the antenna device 2, concave-convex portions 20 that periodically spread in the X-axis direction from the radiation portion 8 are provided on the outer wall surface 4 around the radiation portion 8 so as to surround the radiation portion 8 from both sides in the X-axis direction.
The concave-convex portion 20 is used for reflecting the radio wave radiated from the radiation portion 8 when the radio wave hits an object disposed in front of the radiation direction of the radio wave and is reflected, and when the reflected wave enters the antenna device 2, reflecting the incident wave in a direction different from the incident direction.
In other words, the radar apparatus can be used to detect other objects such as other vehicles and pedestrians located in front of the vehicle in the traveling direction by providing the antenna apparatus 2 in the vehicle such that the X-axis direction in which the plurality of waveguides 10 are arranged is the horizontal direction.
As shown in fig. 3, an object 50 such as a bumper of an automobile or an antenna cover for protecting the antenna device 2 is disposed in front of the radiation direction of the radio wave from the radiation unit 8 of the antenna device 2. Therefore, the radio wave radiated from the radiation section 8 is radiated to the surroundings of the automobile through the object 50, a part of the radio wave is reflected by the object 50, and the reflected wave enters the antenna device 2.
Since the outer wall surface 4 of the antenna device 2 is made of the same metal as the waveguide 10, the incident wave that is reflected by the object 50 and enters the antenna device 2 is reflected by the outer wall surface 4 of the antenna device 2 with low loss.
As a result, superposition reflection occurs in which a part of the radio wave radiated from the antenna device 2 is repeatedly reflected between the object 50 and the outer wall surface 4. When such overlapping reflection occurs, an unnecessary signal component due to the overlapping reflection is superimposed on the reception signal of the antenna device 2, and therefore the detection accuracy of the radar device with respect to the target object is lowered.
Therefore, in the present embodiment, in order to suppress the superposition reflection, the concave-convex portion 20 is provided on the outer wall surface 4 around the radiation portion 8.
The uneven portion 20 includes a plurality of ridges 22 formed linearly so as to be parallel to the central axis O of the waveguide 10 in which the plurality of slits 6 are arranged, and a groove portion 24 sandwiched between the ridges 22 and the ridges 22.
As shown in fig. 4, in the concave-convex portion 20, the widths in the arrangement direction of the ridges 22 and the grooves 24 arranged periodically in the X-axis direction are set to be one-half (λ/2) of the wavelength (λ) of the radio wave transmitted and received by the antenna device 2.
As a result, the reflected waves that are radiated forward in the Z-axis direction from the radiation section 8 and reflected from the object 50 located forward in the radiation direction are reflected by the ridges 22, which are convex portions, and the outer wall surface of the groove 24, which is a concave portion, respectively, but a phase difference occurs in the reflected waves according to the depth H of the groove 24.
Then, due to the phase difference, the reflected wave reflected from the outer wall surface 4 of the antenna device 2 is reflected in a direction different from the incident direction from the object 50 arranged in front of the radiation direction.
In other words, the reflected wave from the object 50 disposed in front in the radiation direction enters the outer wall surface 4 of the antenna device 2 from the Z-axis direction, but the incident wave is reflected from the outer wall surface 4 of the antenna device 2 at an angle different from the incident angle of the incident wave, as indicated by the open arrow in fig. 4.
Therefore, the power of the reflected wave reflected from the outer wall surface 4 of the antenna device 2 toward the object 50 in the radiation direction front is significantly reduced compared to an antenna device without the concave-convex portion 20, and the overlap reflection can be suppressed.
For example, fig. 5A shows the measurement result of the reflected power of the radio wave in the antenna device having no concave-convex portion 20 on the outer wall surface 4, and fig. 5B shows the measurement result of the reflected power of the radio wave in the antenna device 2 of the present embodiment having the concave-convex portion 20 on the outer wall surface 4.
The measurement result indicates the reflection power of the electric wave when the reflection angle changes on the XZ plane and the YZ plane, with the Z-axis direction as the reference angle 0[ deg. ].
As shown in fig. 5A, in the antenna device having no uneven portion 20 on the outer wall surface 4, the reflected power of the incident wave incident from the Z-axis direction is maximum in the Z-axis direction of the reflection angle 0[ deg. ] and decreases as the reflection angle changes in the X-axis direction and the Y-axis direction.
In contrast, in the antenna device 2 of the present embodiment, as shown in fig. 5B, the reflected power is greatly reduced in the range of the reflection angle 0 ± 40[ deg. ] as compared with the antenna device without the concave-convex portion 20. This is because the incident wave is dispersedly reflected in the X-axis direction by the concave-convex portion 20.
As described above, according to the antenna device 2 of the present embodiment, when a reflected wave from the object 50 arranged in front of the radiation direction of the radio wave enters the antenna device 2, the incident wave can be reflected in a dispersed manner in a direction different from the incident direction.
Therefore, even if the radio wave radiated from the radiation section 8 of the antenna device 2 is reflected by the object 50 arranged in front in the radiation direction and the reflected wave enters the antenna device 2, it is possible to suppress the occurrence of the overlapping reflection between the outer wall surface 4 of the antenna device 2 and the object 50.
Thus, according to the antenna device 2 of the present embodiment, unnecessary reflected signal components received by the radiation unit 8 due to superposition reflection can be reduced, and the detection accuracy of the radar device for the target object can be improved.
In addition, in the antenna device 2 of the present embodiment, since it is not necessary to provide a filter such as a frequency selective surface unit in order to suppress the occurrence of the superimposed reflection, it is possible to suppress narrowing of the frequency band of the radio wave that can be transmitted and received and to suppress lowering of the transmission/reception power of the radio wave.
The reflection direction of the radio wave from the outer wall surface 4 of the antenna device 2 can be set by adjusting the phase of the reflected wave from the ridge 22 and the groove portion 24 according to the depth H of the groove portion 24, but the reflection direction can also be set by adjusting the width of the ridge 22.
In other words, since the reflected power from the ridge 22 increases when the width of the ridge 22 is made larger than λ/2, and the reflected power from the ridge 22 decreases when the width of the ridge 22 is made smaller than λ/2, the reflected power from the ridge 22 can be adjusted by adjusting the width of the ridge 22.
Further, by adjusting the reflected power from the ridge 22, the reflection direction of the reflected wave that is synthesized with the reflected wave from the groove 24 and reflected from the outer wall surface 4 of the antenna device 2 can be changed.
Thus, the width of the ridge 22 does not necessarily need to be λ/2, and may be set appropriately according to the reflection direction of the reflected wave from the outer wall surface 4.
In addition, since the groove 24 is only required to allow radio waves to enter the groove 24 and reflect the incident waves on the outer wall surface in the groove 24, the width of the groove 24 may be larger than λ/2. In other words, if the width of the groove 24 is made smaller than λ/2, it is considered that radio waves cannot enter the groove 24 and cannot be reflected, but if the width of the groove 24 is made equal to or larger than λ/2, radio waves entering the antenna device 2 can be reflected by the groove 24.
Therefore, in the antenna device 2 of the present embodiment, by appropriately adjusting the widths of the ridges 22 and the grooves 24 in the concave-convex portions 20 and the depth H of the grooves 24, the reflection direction of the radio wave from the outer wall surface 4 of the antenna device 2 can be arbitrarily set. By setting these parameters, the detection accuracy of the target object in the radar device can be further improved.
It is not necessary to make the depth H of the groove portion 24, in other words, the heights of the ridges 22 all the same, and for example, the heights of the ridges 22 may be set to be different so that the height of the ridge 22 becomes higher as the groove portion becomes farther from the radiation portion 8 or becomes closer to the radiation portion 8.
In the present embodiment, since the plurality of slits 6 provided in the waveguide 10 are elongated and the slits 6 are provided in the waveguide 10 such that the longitudinal direction thereof is the direction of the central axis O of the waveguide 10, the antenna device 2 transmits and receives linearly polarized radio waves.
However, the waveguide slot antenna of the present disclosure may be an antenna device configured such that the slot 6 has a cross shape, for example, and transmits and receives a circularly polarized radio wave. In other words, even in the antenna device that transmits and receives a circularly polarized radio wave, the same effect as described above can be obtained by providing the concave-convex portion 20 around the radiating portion 8 as described above.
[ first modification ]
Here, in the first embodiment, the case where the concave-convex portion 20 is constituted by the plurality of ridges 22 arranged at intervals in the X axis direction in a straight line shape parallel to the central axis O of the waveguide 10 and the groove portions 24 sandwiched between the ridges 22 and the ridges 22 is described as an example.
In contrast, in the antenna device 2 of the first modification, as shown in fig. 6, the concave-convex section 20 includes: a plurality of projections 26 disposed so as to be dispersed at predetermined intervals in the X-axis direction and the Y-axis direction so as to surround the radiation section 8; and a groove portion 24 sandwiched by the projections 26.
Even if the concave-convex portion 20 is configured as described above, if the widths of the projections 26 and the grooves 24 and the depth of the grooves 24 are set as in the above-described embodiment, the reflection direction of the radio wave from the outer wall surface 4 around the radiation portion 8 can be set to an arbitrary direction different from the Z-axis direction.
Therefore, in the antenna device 2 of the present modification as well, as in the first embodiment, the occurrence of overlapping reflection between the outer wall surface 4 of the antenna device 2 and the object 50 disposed forward in the radiation direction can be suppressed.
In the present modification, the projection 26 constituting the concave-convex portion 20 has a square prism shape, but the projection 26 may have a triangular or pentagonal or more prism shape, or may have a circular or elliptical cylindrical shape.
Further, it is not necessary to make all the projections 26 have the same shape, and projections 26 having different shapes may be arranged in a suitably dispersed manner. Further, it is not necessary to make all the projections 26 have the same height from the groove portion 24, and the projections 26 may be provided at different heights, or the shapes of the projections 26 may be different.
In the present modification, the projections 26 are arranged at constant intervals in the X-axis direction and the Y-axis direction, respectively, but the intervals and the arrangement direction may be arbitrarily set, and may be arranged radially from the center of the radiation portion 8, for example.
[ second modification ]
As shown in fig. 7, in the antenna device 2 of the second modification, the concave-convex portion 20 includes a plurality of ridges 28 formed in an annular shape so as to surround the entire periphery of the radiation portion 8 including the plurality of slits 6, and an annular groove portion 24 sandwiched by the ridges 28.
Even if the concave-convex portion 20 is configured as described above, if the widths of the annular ridge 28 and the groove portion 24 and the depth of the groove portion 24 are set as in the above-described embodiment, the reflection direction of the radio wave from the outer wall surface 4 around the radiation portion 8 can be set to an arbitrary direction different from the Z-axis direction.
Therefore, in the antenna device 2 of the present modification as well, as in the first embodiment and the first modification described above, it is possible to suppress occurrence of overlap reflection between the outer wall surface 4 of the antenna device 2 and the object 50 disposed forward in the radiation direction.
In the present modification, the ridge 28 constituting the concave-convex portion 20 is formed in a ring shape, but the ridge 28 may be formed in a ring shape surrounding the radiation portion 8, and the ring shape may be an ellipse or a polygon such as a square.
[ third modification ]
As shown in fig. 8, in the antenna device 2 of the third modification, the concave-convex portion 20 of the outer wall surface 4 provided around the radiation portion 8 is formed by a plurality of inclined surfaces 32, which are formed as a highest portion having the highest height on the radiation portion 8 side and a lowest portion having the lowest height on the side opposite to the radiation portion.
The plurality of slopes 32 are formed so that the heights thereof continuously change from the highest portion to the lowest portion. Each inclined surface 32 is formed in a straight line parallel to the central axis O of the waveguide 10, and each inclined surface 32 is arranged to continuously expand in the X-axis direction.
In other words, in the antenna device 2 of the present modification, the outer wall surface 4 around the radiation section 8 is a reflection surface that changes in a sawtooth wave shape like a fresnel lens. The widths of the plurality of inclined surfaces 32 constituting the reflecting surface in the X axis direction are set to be λ/2 or more, and the widths are set to be longer as the inclined surfaces are closer to the radiation section 8.
Even if the concave-convex portion 20 is constituted by a plurality of continuous inclined surfaces 32 as described above, the reflection direction of the radio wave from the outer wall surface 4 around the radiation portion 8 can be set to an arbitrary direction different from the Z-axis direction by adjusting the width of the inclined surfaces 32 and the height from the lowest portion to the highest portion.
Therefore, in the antenna device 2 of the present modification as well, as in the first embodiment and the first and second modifications described above, it is possible to suppress occurrence of overlapping reflection between the outer wall surface 4 of the antenna device 2 and the object 50 disposed forward in the radiation direction.
[ fourth modification ]
As shown in fig. 9, in the antenna device 2 of the fourth modification, the concave-convex portion 20 is constituted by a plurality of inclined surfaces 38, as in the third modification. The plurality of slopes 38 are formed in an annular shape so as to surround the entire periphery of the radiation portion 8, and each slope 38 is arranged so as to continuously extend from the radiation portion 8 to the periphery thereof as a center.
Even if the concave-convex portion 20 is constituted by the plurality of annular inclined surfaces 32 as described above, the direction of reflection of the radio wave from the outer wall surface 4 around the radiation portion 8 can be set to an arbitrary direction different from the Z-axis direction by adjusting the width and height of the inclined surface 32, as in the antenna device 2 of the third modification.
Accordingly, in the antenna device 2 of the present modification as well, as in the first embodiment and the first, second, and third modifications, it is possible to suppress occurrence of overlapping reflection between the outer wall surface 4 of the antenna device 2 and the object 50 disposed forward in the radiation direction.
In the present modification, the plurality of inclined surfaces 38 constituting the concave-convex portion 20 do not necessarily need to be formed in a circular ring shape, and the ring shape may be an elliptical shape or a polygonal shape such as a square shape, as in the case of the ridge 28 of the second modification.
[ second embodiment ]
As shown in fig. 10, the waveguide slot antenna according to the present embodiment is an antenna device 2 used in a millimeter wave radar device mounted on an automobile or the like, and includes a plurality of waveguides 10 shown in fig. 2, as in the first embodiment.
The outer wall surface 4 around the radiation section 8 formed by the slits 6 provided in the plurality of waveguides 10 is provided with a plurality of linear protrusions 42 arranged at predetermined intervals so as to be inclined at an angle of 45 degrees with respect to the Y axis along the central axis O of the waveguide 10.
In other words, in the present embodiment, the concave-convex portion 20 is formed by the plurality of ridges 42 arranged at an inclination angle of 45 degrees with respect to the Y axis and the X axis, and the groove portion 44 sandwiched by the respective ridges 42.
In the concave-convex portion 20, the widths in the arrangement direction of the ridges 42 and the grooves 44 are set to be one-half (λ/2) of the wavelength (λ) of the center frequency of the radio wave transmitted and received by the antenna device 2. The depth of the groove 44 is set to 3 · λ/2+n · λ (where n is an integer).
In the antenna device 2 of the present embodiment configured as described above, when the linearly polarized radio wave radiated from the radiation unit 8 hits the object 50 and is reflected, and the reflected wave enters the antenna device 2, the polarization plane of the incident wave is rotated by 90 degrees and is reflected at the concave-convex portion 20.
In other words, as shown in fig. 11, when the electric field Win of the incident wave is divided into an electric field component WA parallel to the central axis of the groove portion 44 and an electric field component WB perpendicular thereto, the electric field component WA is reflected at the same phase in the groove portion 44 regardless of the depth of the groove portion 44.
On the other hand, since the width of the groove 44 is λ/2, the electric field component WB is reflected in the groove 44, and causes phase rotation together with reflection from the ridge 42. As a result, by setting the depth of the groove portion 44 as described above, the electric field component WB is reflected in an opposite phase, and the reflected component WBR is combined with the reflection of the electric field component WA.
Therefore, as shown in fig. 10, a linearly polarized radio wave radiated from the antenna device 2 is reflected by the collision object 50, and an incident wave incident on the antenna device 2 is reflected by rotating the polarization plane by 90 degrees at the concave-convex portion 20 provided on the outer wall surface 4.
For example, fig. 12A and 12B show measurement results of measuring the power of reflected waves when a radio wave having the same polarization plane as that of a linearly polarized radio wave radiated from the radiation unit 8 is incident on the antenna device without the concave-convex portion 20 on the outer wall surface 4 and the antenna device 2 according to the present embodiment, respectively.
As shown in fig. 12A, in the antenna device having no uneven portion 20 on the outer wall surface 4, the reflected power of the main polarization component, which is the same polarization plane as the incident wave, in the reflected wave is significantly increased as compared with the reflected power of the orthogonal polarization component whose polarization plane is rotated by 90 degrees with respect to the main polarization.
In contrast, in the antenna device 2 of the present embodiment, as shown in fig. 12B, the reflected power of the main polarization component is largely reduced in the vicinity of the reflection angle 0[ deg. ] and the reflected power of the orthogonal polarization component is increased to the same level as the reflected power of the main polarization, as compared with an antenna device without the concave-convex portion 20.
Therefore, it is also known from the measurement result that the incident wave to the antenna device 2 is reflected by rotating the polarization plane by 90 degrees at the concave-convex portion 20 provided on the outer wall surface 4.
Therefore, in the antenna device 2 of the present embodiment, even if the reflected wave from the outer wall surface 4 of the antenna device 2 hits the object 50 and is reflected, a radio wave whose polarization plane is rotated by 90 degrees with respect to the receivable radio wave is incident on the antenna device 2.
Thus, according to the antenna device 2 of the present embodiment, it is possible to suppress the reception of the reflected wave generated by the overlap reflection between the object 50 in front in the radiation direction and the antenna device 2 at the antenna device 2.
Therefore, even if the overlap reflection occurs between the object 50 in front in the radiation direction and the antenna device 2, the reflected wave from the target object outside the vehicle to be detected can be received without being affected by the overlap reflection, and the detection accuracy of the target object by the radar device can be suppressed from being lowered.
In addition, in the antenna device 2 of the present embodiment, it is not necessary to provide a filter such as the above-described frequency selective surface element in order to suppress the occurrence of the superposition reflection, and therefore, similarly to the first embodiment, it is possible to suppress the deterioration of the transmission/reception characteristics of the antenna device 2 due to the filter.
In the present embodiment, the ridges 42 constituting the concave-convex section 20 are provided to be inclined at an angle of 45 degrees with respect to the Y axis along the central axis O of the waveguide 10, but this is for reflecting the incident wave by rotating the polarization plane by 90 degrees on the outer wall surface 4 of the antenna device 2.
However, since the power of the reflected wave due to the superposition reflection received by the radiation unit 8 can be reduced by rotating the polarization plane of the incident wave, the inclination angle of the ridge 42 with respect to the Y axis does not need to be constant at 45 degrees, and can be changed as appropriate.
[ other embodiments ]
While the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and can be implemented in various modifications.
For example, in the above-described embodiment, a case has been described as an example in which the antenna device 2 as a waveguide slot antenna includes a plurality of waveguides 10 in which a plurality of slots 6 are arranged in a line in the central axis direction, and the plurality of waveguides 10 are arranged in parallel in the direction orthogonal to the central axis of each waveguide 10.
However, even in the antenna device including the waveguide 10 in which the plurality of slits 6 are arranged in a line in the central axis direction, the technique of the present disclosure can be applied in the same manner as in the above-described embodiment or modification, and the same effects as described above can be obtained.
In the above-described embodiment, the case where the antenna device 2 as a waveguide slit antenna is used in a radar device for detecting a target object installed in an automobile or the like has been described as an example, but the waveguide slit antenna of the present disclosure can also be applied to a communication device or the like that performs wireless communication.
Further, when the antenna device of the present embodiment is applied to a communication device, it is possible to suppress a reflected wave reflected from an object such as an antenna cover disposed forward in the radiation direction from being reflected by overlapping between the antenna device and the object, and to suppress a decrease in communication accuracy of the communication device.
The shape and size of the concave-convex portion 20 described in the above embodiments are examples, and the shape and size can be appropriately changed within a range in which the reflection characteristics capable of suppressing the influence of the superimposed reflection can be obtained in the antenna device 2.
The antenna device 2 may be configured by appropriately combining the shapes of the concave-convex portions 20 of the above embodiments and providing the concave-convex portions on the outer wall surface 4.
Claims (14)
1. A waveguide slot antenna is provided with:
a waveguide (10) provided with a plurality of slits (6) as radiation sections (8) for radiating radio waves, the slits being provided at predetermined intervals in the central axis direction; and
an uneven portion (20) provided on an outer wall surface (4) around the radiation portion so as to periodically spread from the radiation portion,
the concave-convex portion is configured to reflect an incident wave of the radio wave from the radiation portion, which is incident from the front in the radiation direction, in a direction different from the incident direction of the incident wave.
2. The waveguide slot antenna of claim 1,
a plurality of waveguides provided in parallel such that the radiating portions are arranged in a direction orthogonal to the central axis of each waveguide,
the uneven portion is provided so as to surround the radiation portions of the plurality of waveguides.
3. The waveguide slot antenna according to claim 1 or claim 2,
the width of the concave portions between the convex portions and the convex portions among the concave and convex portions periodically provided on the outer wall surface of the waveguide is set to be equal to or more than one half (λ/2) of the wavelength (λ) of the radio wave radiated from the waveguide slot antenna.
4. The waveguide slot antenna of claim 3,
the uneven portions provided periodically on the outer wall surface of the waveguide are set such that the width of the uneven portions in the periodic arrangement direction is one-half (λ/2) of the wavelength (λ) of the radio wave at each of the concave portions and the convex portions.
5. The waveguide slot antenna according to any one of claims 1 to 4,
the uneven portion includes a plurality of ridges (22) formed linearly in parallel with the central axis of the waveguide in which the plurality of slits are arranged, and a groove portion (24) sandwiched by the ridges.
6. The waveguide slot antenna according to any one of claims 1 to 4,
the uneven portion includes a plurality of projections (26) and a groove portion (24) sandwiched by the projections, and the projections are respectively arranged at predetermined intervals in an axial direction parallel to a central axis of the waveguide in which the plurality of slits are arranged and in an axial direction orthogonal to the central axis.
7. The waveguide slot antenna according to any one of claims 1 to 4,
the uneven portion includes a plurality of ridges (28) and a groove portion (24) sandwiched by the ridges, and the ridges are formed in a ring shape so as to surround the radiation portion of the waveguide.
8. The waveguide slot antenna according to claim 1 or claim 2,
the relief portion includes a plurality of inclined surfaces (32, 38) configured to: the radiation unit is formed to have a highest portion at which the radiation unit side is highest, and a lowest portion at which the radiation unit side is lowest, and the height of the radiation unit continuously changes from the highest portion to the lowest portion and extends from the radiation unit.
9. The waveguide slot antenna of claim 8,
the plurality of slopes are arranged in a zigzag shape so as to extend continuously from the radiating portion, and the width of each slope in the arrangement direction is set to be equal to or more than one half (λ/2) of the wavelength (λ) of the radio wave radiated from the waveguide slot antenna.
10. The waveguide slot antenna according to claim 8 or claim 9,
the plurality of inclined surfaces are formed linearly so as to be parallel to the central axis of the waveguide in which the plurality of slits are arranged.
11. The waveguide slot antenna according to claim 8 or claim 9,
the plurality of slopes are formed in a ring shape so as to surround the radiation portion of the waveguide.
12. A waveguide slot antenna is provided with:
a waveguide (10) provided with a plurality of slits (6) as radiation sections (8) for radiating radio waves, the slits being provided at predetermined intervals in the central axis direction; and
a plurality of linear protruded strips (42) which are arranged on the outer wall surface around the radiation part at intervals in a manner of inclining at a predetermined angle relative to the central axis of the waveguide,
the plurality of ridges are configured such that, by the ridges and the groove sections (44) sandwiched by the ridges, an incident wave of a radio wave from the radiation section, which is incident from the front in the radiation direction, is reflected so that the polarization plane of the incident wave is rotated by a predetermined angle.
13. The waveguide slot antenna of claim 12,
a plurality of waveguides arranged in parallel such that the radiating portion is arranged in a direction orthogonal to the central axis of each waveguide,
the plurality of ribs are arranged around the radiating portions of the plurality of waveguides.
14. The waveguide slot antenna according to claim 12 or claim 13,
the plurality of ridges are provided around the radiating portion so as to be inclined at 45 degrees with respect to the central axis of the waveguide,
in the plurality of ribs and the groove portion, a width of the plurality of ribs in an arrangement direction is set to be one half (λ/2) of a wavelength (λ) of a radio wave radiated from the waveguide slot antenna, and a depth of the groove portion is set to be 3 · λ/2+n · λ, where n is an integer.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2020-090692 | 2020-05-25 | ||
| JP2020090692A JP7211398B2 (en) | 2020-05-25 | 2020-05-25 | waveguide slot antenna |
| PCT/JP2021/018643 WO2021241305A1 (en) | 2020-05-25 | 2021-05-17 | Waveguide slot antenna |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115668645A true CN115668645A (en) | 2023-01-31 |
Family
ID=78744650
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202180037510.4A Pending CN115668645A (en) | 2020-05-25 | 2021-05-17 | Waveguide tube slit antenna |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US20230099058A1 (en) |
| JP (1) | JP7211398B2 (en) |
| CN (1) | CN115668645A (en) |
| DE (1) | DE112021002988T5 (en) |
| WO (1) | WO2021241305A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20240145929A1 (en) * | 2021-03-04 | 2024-05-02 | Dai Nippon Printing Co., Ltd | Frequency selective reflector and reflecting structure |
| EP4191141A1 (en) * | 2021-12-03 | 2023-06-07 | BSH Hausgeräte GmbH | Household appliance device |
| DE102022113327A1 (en) * | 2022-05-25 | 2023-11-30 | Friedrich-Alexander-Universität Erlangen-Nürnberg, Körperschaft des öffentlichen Rechts | Antenna structure |
| CN115458910B (en) * | 2022-08-22 | 2024-07-02 | 四川大学 | Modularized dual-frequency AMC load filter antenna manufactured by combining 3D printing and PCB modes |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE758660A (en) * | 1969-11-13 | 1971-05-10 | Hein Lehmann Ag | COATING INFLUENCING MARKING BY RADAR |
| JPS59208903A (en) * | 1983-05-12 | 1984-11-27 | Nec Corp | Support of effective area antenna |
| JPH02186703A (en) * | 1989-01-13 | 1990-07-23 | Naohisa Goto | Slot array antenna of waveguide |
| FR2879359B1 (en) | 2004-12-15 | 2007-02-09 | Thales Sa | BROADBAND ELECTRONIC SCANNING ANTENNA |
| JP4727568B2 (en) | 2006-12-28 | 2011-07-20 | 三菱電機株式会社 | Waveguide array antenna |
| CN102723541B (en) | 2012-06-14 | 2014-06-25 | 北京航空航天大学 | Method for optimizing cross-shaped annular slot frequency selection surface unit structural body and conformal antenna housing with low radar cross-section (RCS) |
| WO2019082164A1 (en) | 2017-10-27 | 2019-05-02 | Thales Canada Inc. | Near-grazing retroreflectors for polarization |
| JP2020090692A (en) | 2018-12-04 | 2020-06-11 | Ｊｆｅスチール株式会社 | Bearing unit and continuous annealing furnace |
-
2020
- 2020-05-25 JP JP2020090692A patent/JP7211398B2/en active Active
-
2021
- 2021-05-17 DE DE112021002988.6T patent/DE112021002988T5/en active Pending
- 2021-05-17 WO PCT/JP2021/018643 patent/WO2021241305A1/en active Application Filing
- 2021-05-17 CN CN202180037510.4A patent/CN115668645A/en active Pending
-
2022
- 2022-11-22 US US18/058,075 patent/US20230099058A1/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| WO2021241305A1 (en) | 2021-12-02 |
| DE112021002988T5 (en) | 2023-03-09 |
| JP7211398B2 (en) | 2023-01-24 |
| US20230099058A1 (en) | 2023-03-30 |
| JP2021190719A (en) | 2021-12-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN115668645A (en) | Waveguide tube slit antenna | |
| CN107004960B (en) | Antenna device | |
| US11079472B2 (en) | Antenna apparatus | |
| EP3096400B1 (en) | Antenna device, wireless communication apparatus, and radar apparatus | |
| US11575196B2 (en) | Antenna device | |
| CN108886198B (en) | Antenna device | |
| US7453411B2 (en) | Antenna device and radar apparatus including the same | |
| US11121461B2 (en) | Antenna device | |
| EP3525287B1 (en) | Antenna, sensor, and vehicle mounted system | |
| US8593369B2 (en) | Antenna assembly | |
| JP2007235287A (en) | Vehicle-mounted electromagnetic wave radar | |
| US20180212328A1 (en) | Wireless device | |
| US11056766B2 (en) | Antenna apparatus | |
| CN113661610A (en) | Radar device and bracket for radar device | |
| US9263791B2 (en) | Scanned antenna having small volume and high gain | |
| JP6510394B2 (en) | Antenna device | |
| CN111903001B (en) | Reflection reducing device | |
| JP7189092B2 (en) | radar equipment | |
| WO2019039407A1 (en) | Antenna device | |
| JP5690707B2 (en) | Antenna and communication system | |
| US11639993B2 (en) | Radar apparatus | |
| SU280574A1 (en) | ||
| RU2530281C2 (en) | Broadband antenna system | |
| JP2022027059A (en) | Radar device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |